A number of disorders affecting the cognitive development of children are associated with short-term auditory memory impairments. These impairments can affect the development of attention, memory, language, and as a consequence affect achievement in later life. However, very little data have been reported concerning the normal maturation of short-term memory stores in childhood, especially with respect to the co-development of the physiological and anatomical substrates of those functions. Preliminary evidence from this laboratory concerning auditory sensory memory (echoic memory) have broad implications for the development of working memory. Maturational changes in working memory have been identified in previous research, but questions remain concerning the mechanisms driving the change. We hypothesize that developmental alterations in the persistence of echoic memory underlie the increased capacity of working memory. The long-term goal of the project is to better understand the development of early auditory memory, both in functional and structural terms, so that this knowledge may be applied to clinical disorders where dysfunction in these systems exist, such as developmental dyslexia. Using magnetoencephalographic and psychoacoustic methods, we propose to study the development of echoic memory duration in children. We hypothesize a significant decrease in the duration of echoic memory during the years spanning preadolescence and adolescence. We also believe that gender will be a mediating factor in the development of echoic memory, and hypothesize that females will mature than males. Further, consistent with our preliminary data we hypothesize that the right hemisphere echoic trace will change more rapidly than the left hemisphere trace. We will also use anatomical information from magnetic resonance imaging, combined with MEG source lateralization, to measure the location of the neural generators involved in echoic memory. We hypothesize that the cerebral asymmetries usually present in adult males will not be present before adolescence. To better understand the constraints which echoic memory duration places upon working memory, we will relate the two systems' development in our studies.